Submitted to: Crop Protection
Publication Type: Proceedings
Publication Acceptance Date: 11/11/2003
Publication Date: 12/15/2003
Citation: Hartman, G.L., Miles, M.R., Frederick, R.D. 2003. Soybean rust: will resistance work?. Crop Protection.
Technical Abstract: The Asian soybean rust, Phakopsora pachyrhizi, was first found in the U.S. in Hawaii in 1994. After 1994, the pathogen was discovered in two countries in Africa and three countries in South America. The rapid spread of P. pachyrhizi and the potential for severe yield losses makes this the most destructive foliar disease of soybean. Specific resistance to P. pachyrhizi occurs as four single dominant genes. The Rpp1 was described as having an immune reaction when inoculated with a few isolates, including India 73-1. Inoculation of most rust isolates on Rpp1 or the other genes produces a resistant red-brown (RB) lesion with no or sparsely sporulating uredinia. The RB lesion type is considered to be a resistant lesion type when compared to a fully susceptible TAN lesion. Single gene resistance has not been durable and the usefulness of the single genes was lost soon after the sources were identified. Partial resistance, or rate reducing resistance, is also known in soybean. Lines with partial resistance in field evaluations are rated as moderately resistant, since fewer lesions develop on plants throughout the season. Yield stability, or tolerance, refers to the strategy of selecting genotypes with high yield potential and less yield loss from soybean rust. Cultivars with yield stability may have some partial resistance not characterized or selected for in breeding programs.